CGI1746 is a potent and highly selective small-molecule Btk inhibitor with IC50 of 1.9 nM.

Treatment with CGI1746 at a dose of 100 mg/kg, administered subcutaneously twice daily, resulted in a significant suppression (97%) of overall clinical arthritis symptoms. In a positive anti-collagen type II antibody-induced arthritis model, CGI1746 significantly reduced levels of TNFα, IL-1β, and IL-6, as well as MCP-1 and MIP-1α mRNA and protein. In mice and rats with arthritis, CGI1746 demonstrated superior efficacy compared to TNFα blockade, significantly lowering clinical scores while also reducing joint inflammation.

CGI1746 effectively inhibits the proliferation of CD27+IgG+ B cells isolated from the tonsils of four donors, with an average IC50 of 112 nM. It completely suppresses B cell proliferation induced by anti-IgM in both mice and humans, with IC50s of 134 nM and 42 nM, respectively, yet does not affect T cell proliferation induced by anti-CD3 and anti-CD28. In macrophages, CGI1746 eliminates the production of TNFα, IL-1β, and IL-6 triggered by FcγRIII. It also efficiently inhibits the production of TNFα and IL-1β in human monocytes stimulated by immobilized or soluble immune complexes, and to a lesser extent, reduces IL-6 production. CGI1746 shows high specificity and selectivity for Btk, being ~1,000 times more selective than for Tec and Src family kinases.

CGI-1746 is dissolved in DMSO. 5×103?DU145 cells or 104?LNCaP cells per well, grown on 96 well plates for 24h, are treated with 1 to 30?μM BTK inhibitors. Cells are fixed after 72h with 2.5% formaldehyde, and stained with Hoechst 33342. Control cells are treated with DMSO. Cell images are acquired using an IN Cell Analyzer 2200 high content imaging system, with a 20X objective. At least 9 fields are imaged per single well of each experiment. Cell numbers are determined and statistics performed using IN Cell Investigator 3.4 high content image analysis software. Each experiment is replicated 3 times, and data are presented as mean±SD. Results are considered significant if p < 0.05.